We intend to continue retrograde catheterization of the carotid arteries of goats. Each catheter will be treated either with goat albumin or directly with single different fatty acids. The albumin will be "bound" to the catheters by glutaraldehyde. Studies will be done to measure desorption kinetics of albumin and the fatty acids radionuclide tracers. Retention of platelets onto the carotid catheter will be assessed acutely and continuously using 111Indium labeled autologous platelets. Work will also be done to correlate differences in 111Indium accumulation among catheters. Finally correlations between acute and chronic studies will be performed using as endpoints platelet kinetics, thrombus weight and analysis, and analysis of the catheter's surface and bulk properties.